Here is an example of how ReSharper applies code inspection to validate HTML code and underlines obsolete or non-standard elements and attributes.

Path Mapping

As you develop a web application, you deploy it onto a destination server from time to time. However, paths to files in the destination environment may differ from paths in your local environment, which makes analysing paths difficult. To make life easier, ReSharper highlights unknown paths and suggests several quick-fixes: Click Set path mapping to open the Path mapping dialog where you can create and change path mapping rules. Click Ignore or Substitute to specify what kind of rule it should be. Depending on the choice, type a path that should be ignored or a path that should be substituted and a path that is a substitution. You can create as many rules as you need and manage them at any time. Open the Visual Studio Properties window for your web project and find the Path mapping property. If some path rules are defined, then its value is Custom, otherwise - Not set. To open the Path mapping dialog, click the nearby button.